.TH std::ranges::destroy 3 "2024.06.10" "http://cppreference.com" "C++ Standard Libary"
.SH NAME
std::ranges::destroy \- std::ranges::destroy

.SH Synopsis
   Defined in header <memory>
   Call signature
   template< no-throw-input-iterator I, no-throw-sentinel-for<I> S >

       requires std::destructible<std::iter_value_t<I>>               \fB(1)\fP \fI(since C++20)\fP

   constexpr I destroy( I first, S last ) noexcept;
   template< no-throw-input-range R >

       requires std::destructible<ranges::range_value_t<R>>           \fB(2)\fP \fI(since C++20)\fP

   constexpr ranges::borrowed_iterator_t<R> destroy( R&& r )
   noexcept;

   1) Destroys the objects in the range [first, last), as if by

 for (; first != last; ++first)
     std::ranges::destroy_at(std::addressof(*first));
 return first;

   2) Same as \fB(1)\fP, but uses r as the source range, as if using ranges::begin(r) as
   first and ranges::end(r) as last.

   The function-like entities described on this page are niebloids, that is:

     * Explicit template argument lists cannot be specified when calling any of them.
     * None of them are visible to argument-dependent lookup.
     * When any of them are found by normal unqualified lookup as the name to the left
       of the function-call operator, argument-dependent lookup is inhibited.

   In practice, they may be implemented as function objects, or with special compiler
   extensions.

.SH Parameters

   first, last - iterator-sentinel pair denoting the range of elements to destroy
   r           - the range to destroy

.SH Return value

   An iterator compares equal to last.

.SH Complexity

   Linear in the distance between first and last.

.SH Possible implementation

   struct destroy_fn
   {
       template<no-throw-input-iterator I, no-throw-sentinel-for<I> S>
           requires std::destructible<std::iter_value_t<I>>
       constexpr I operator()(I first, S last) const noexcept
       {
           for (; first != last; ++first)
               std::ranges::destroy_at(std::addressof(*first));
           return first;
       }

       template<no-throw-input-range R>
           requires std::destructible<std::ranges::range_value_t<R>>
       constexpr std::ranges::borrowed_iterator_t<R> operator()(R&& r) const noexcept
       {
           return operator()(std::ranges::begin(r), std::ranges::end(r));
       }
   };

   inline constexpr destroy_fn destroy{};

.SH Example

   The following example demonstrates how to use ranges::destroy to destroy a
   contiguous sequence of elements.


// Run this code

 #include <iostream>
 #include <memory>
 #include <new>

 struct Tracer
 {
     int value;
     ~Tracer() { std::cout << value << " destructed\\n"; }
 };

 int main()
 {
     alignas(Tracer) unsigned char buffer[sizeof(Tracer) * 8];

     for (int i = 0; i < 8; ++i)
         new(buffer + sizeof(Tracer) * i) Tracer{i}; //manually construct objects

     auto ptr = std::launder(reinterpret_cast<Tracer*>(buffer));

     std::ranges::destroy(ptr, ptr + 8);
 }

.SH Output:

 0 destructed
 1 destructed
 2 destructed
 3 destructed
 4 destructed
 5 destructed
 6 destructed
 7 destructed

.SH See also

   ranges::destroy_n  destroys a number of objects in a range
   (C++20)            (niebloid)
   ranges::destroy_at destroys an object at a given address
   (C++20)            (niebloid)
   destroy            destroys a range of objects
   \fI(C++17)\fP            \fI(function template)\fP
